Rotary impact attachment



Nov; 21, 1961 E. J. ONDECK 3,009,552

ROTARY IMPACT ATTACHMENT Original Filed June 9, 1955 2 Sheets-Sheet 1 IN VEN TOR.

merfayza ea Nov. 21, 1961 E. J. ONDECK 3,009,552 ROTARY IMPACT ATTACHMENT Original Filed June 9, 1955 2 Sheets-Sheet 2 INVENTOR.

United States atent Ofiice 3,009,552 Patented Nov. 21, 1961 Claims. (Cl. 192-305) This invention relates to rotary impact tools and more particularly to a screw driver or nut runner effecting impact engagement and positive disengagement of clutch members therein for unusual efliciency and power.

The present application is a division of my co-pending application, U.S. Serial No. 514,354, filed June 9, 1955, now U.S. Patent No. 2,916,117.

With conventional impact type clutch drives for power tools, interaction between the clutch members is accompanied by bounce of the whole tool itself, or of the working head on the work, or is accomplished with cam surfaces or sliding engagements which absorb power frictionally or otherwise. In any of these ways, power is lost in the tool which should be expended as torque impulse sharply delivered.

Consequently, it is one of the objects of the invention to provide an externally vibrationless impact clutch drive wherein impact striking power is stored in members that receive the power and deliver the power torquewise without cams and without frictional losses.

A further object of the invention is to provide an improved impact clutch which is reversible in direction of rotation and all moving parts can be lubricated without loss of power.

It is also an objective of the present invention to provide a rotary impact tool which does not clear the engagement between one clutch member and another until a predetermined amount of torque is developed between them, so that successive impacts between the clutch elements are rapid and uniform hammer-type blows.

Another object is to provide a rotary impact tool having means for accumulating energy when the clutch members thereof are engaged and for driving one of the clutch members along a helical path with the energy thus accumulated when the clutch members are disengaged to convert such energy into high impact torque.

Another object is to provide a plurality of substantially sector-shaped teeth on the mating faces of each of the clutch members of the rotary impact tool of the invention, the radially aligned sides of the teeth being substantially vertical for square impact engagement along the interfaces to convert accumulated energy efliciently into pulsating torque expenditures of energy.

Another object is to provide means adapted to axially bias the clutch members into engagement and to maintain the clutch members engaged with increasing torque accumulating effect until a predetermined level or torque is achieved before each impact blow is delivered.

Another object of the invention is to provide a rotary impact tool of the type indicated which may be driven in either direction of rotation, and with a reversible gear system adapted to effect selective reversal of the screw driver or nut runner if the source of power is not readily reversible.

Other objects and advantages of the invention will become evident as the description proceeds in accordance with the drawings, in which:

FIG. 1 is a vertical sectional view of a rotary impact tool and clutch elements therefor taken along line 11 of FIG. 2;

FIG. 2 is a horizontal sectional View of the impact clutch member 22 tool of the invention taken along the line 2-2 of FIG. 1;

FIG. 3 is a horizontal sectional view of the tool of the invention taken along the lines 3-3 of FIG. 1;

FIG. 4 is an exploded perspective View of the clutch elements of the invention in a particular embodiment thereof;

FIG. 5 is a fragmentary side elevational view of the embodiment of FIG. 4 showing the clutch elements in driving engagement;

FIG. 6 is a similar view to that seen in FIG. 5 showing the clutch elements in disengaged relation.

Referring now to FIG. 1, a particular embodiment of the rotary impact tool 10 of the invention is disclosed wherein a casing 12 having a cap 14 secured to a cylindricai body portion 16 is adapted to have journalled therethrough the spindle 18. The spindle 18 has an upper portion 19 of reduced diameter adapted to be keyed to a prime mover (not shown) conventionally used to power a screw driver or nut runner of conventional form, and a lower portion 21 of reduced diameter journalled the clutch member 20. The clutch member 20 is journailed at the same level in the casing 16 to maintain alignment of parts and their relative working positions.

A complementary clutch member 22 is provided which is adapted to engage in rotary drive relationship with the clutch member 20 by means of complementary teeth 24 and 26 on the clutch elements 20 and 22 respectively, as seen in FIG. 3. The teeth 24 and 26 are preferably given a sector-shaped configuration and their radial sides 27 are preferably substantially vertical as shown in FIGS. 3, 4 and 5 so that the driving engagement either by rotary pressure or impact blow is transmitted from the clutch member 22 to member 20 solely as torque, as will be hereinafter described, the relative axial movement being small between the clutch members, and there being no axial component of the active or reactive forces exerted between the impact faces themselves.

A bracket 30 of preferably annular configuration is fixedly secured adjacent the cap 14 to the spindle 18 by means of a suitable key and groove construction or the like (not shown), and a plurality of flat, elongated, laterally and torsionally flexing spring elements 28 having laterally extending ears 29 at the ends thereof are secured in radial slots 32 and 34 having enlarged portions 33 and 35 respectively in circumferential direction or forming L-shaped slots of bracket 30 and clutch member 22 re spectively with the planes thereof in resting position disposed radially of the spindle 18. The spring connection members 28 are normally disposed in vertical axial alignment with the spindle 18 to exert a downward and forward force adapted when flexed to drive and hold the respective clutch members 20 and 22 in mating engagement with each other. Accordingly, when torque is applied to the spindle, the teeth 24 on the upper clutch member 22 engage the teeth 26 on the lower clutch member 20 until the torque increases to a predetermined threshold level. During this transmission of torque, the spring elements 28 will be given a partial twist and lateral flexing, asseen in FIG. 6, to store power. When the torque exceeds the predetermined level, the amount of twist and flexing in the elements 28 will foreshorten them along the vertical axis sufllciently to lift the upper and the teeth 24 thereof above the clutch member 20 and out of engagement with the teeth 26 thereon.

The springs thus serve not only as accumulators of a collective power, but will lift the teeth 24 over the surface of the teeth 26. Then when the teeth are released from engagement the members 28 under their stored power exert counter-axial and counter-torque forces in their effort to recover their resting position. Each tooth on the member 22 will follow an inclined path defining a portion of a curve which ends substantially normal to the vertical face of a tooth upon the member 20 after the teeth 24 become disengaged with the teeth 26. The resultant horizontal component of the vector will, from accelerated momentum of member 20, be several times the torque applied to the spindle 18, so that the member 22 will impart a heavy impact torque to member 20 when teeth 24 strike the teeth 26 along their vertical interfaces.

It will be appreciated that each time the aforementioned predetermined amount of torque for spindle 18 has been reached, the action described will follow and be uniform throughout a rapid succession of impacts to turn the nut or screw. Moreover, the storage and expenditure of energy will be unusually efficient in the operation of the tool because frictional losses are eliminated. In fact, lubrication of the teeth will not reduce the striking power.

As seen in FIG. 4, it is preferred to use a pair of oppositely-aligned teeth on each clutch member for rotation in either direction, but this feature of the invention may be varied without altering the essential conception thereof.

An impact tool of unusual versatility and effectiveness has thus been provided, having means for positively effecting disengagement of the clutch members without friction so that greater uniformity of action with a maximum of torque is possible. correspondingly, a positive driving accelerated momentum action for a golfclub-like whip engagement of the clutch members is achieved which transmits all of the energy accumulated during engagement of the clutch members directly into torque force for the nut runner or screw driver. Thus the ratio of the effective power of the tool to the power of the prime mover is greater than conventionally experienced during substantially the entire operation of tightening or loosening a bolt or inserting or removing a screw.

While I have herein set forth a particular embodiment of the invention in considerable detail, it will be readily apparent that considerable change in these details may be made without departing from the spirit and principles of the invention, as set forth in the following claims.

I claim:

1. In a rotary impact tool, a power spindle, a bracket member secured axially to said spindle, both of said members having radial slots enlarged in a circumferential direction intermediate their axially spaced edges, a clutch member disposed in spaced relation to said bracket member and journalled slidably on said spindle, a plurality of flat spring metal blades interconnecting said bracket member and clutch member offset laterally at their radial outer edges and disposed in said enlargements to support said member against relative axial movement between the ends of the blades and the respective members and with their planes disposed normally radially around the axis of rotation of said spindle, a second clutch member journalled on said spindle, and a plurality of teeth formed integrally on each of said clutch members, adapted to intermesh with the teeth on the other of said clutch members, said metal blades being adapted to hold said clutch members in normally intermeshed relation when straight and to lift said firstnamed clutch member out of engagement with said second-named clutch member when distorted out of their planes upon application of a predetermined amount of torque between said bracket and said first-named clutch member and to return said first-named clutch member along a downwardly helical path upon disengagement of said first-named clutch member to impart impact torque to said second clutch member.

2. In a rotary impact tool, a power spindle, a bracket member secured axially to said spindle, a first clutch member disposed in spaced relation to said bracket member and journalled slidably on said spindle, a plurality of fiat spring metal blades secured at opposite ends to said bracket member and first clutch member in interconnecting relationship and with their planes disposed normally radially around the axis of rotation of said spindle, a second clutch member journalled on said spindle, and a plurality of teeth formed integrally on each of said clutch members adapted to intermesh with the teeth on the other of said clutch members, said metal blades being adapted to hold said clutch members in normally intermeshed relation when straight and to lift said first clutch member out of engagement with said second clutch member when distorted out of their planes upon application of a predetermined amount of torque between said bracket and said first clutch member and to return said first clutch member along a downwardly helical path upon disengagement of said clutch members to impart impact torque to said second clutch member, said securement of the metal blades at their opposite ends comprising corresponding radial grooves in the surfaces of said first clutch member and said bracket member facing each other and having lateral offsets a spaced distance from the facing surfaces and said metal blades have laterally bent ears on their ends received in said offsets against relative axial movement with respect thereto.

3. In a rotary impact tool, a cylindrical casing, a power driven spindle journalled in one end of said casing, a first clutch member journalled on said spindle at the other end of said casing, a second clutch member slidably and rotatably mounted on said spindle to engage said first clutch member and having radially opening slots of L- shaped cross section, a plurality of flat spring blades secured at one end to said spindle against relative axial displacement with respect thereto and at the other end having ends bent laterally to engage in said L-shaped slots to hold said second clutch member against relative axial displacement with respect thereto, and a plurality of integral sector-shaped teeth on each of the mating faces of said clutch members, said spring blades being adapted to bias said second clutch member into mating engagement with said first clutch member under resting conditions and to lift said second clutch member out of engagement with said first clutch member upon development of a predetermined amount of torque between said clutch members, said spring blades accumulating torsional energy during engagement of said clutch members under torque loads to impel said second clutch member along a helical path into impact engagement with said first clutch member upon disengagement thereof.

4. The device according to claim 3 wherein the sides of said sector-shaped teeth are substantially perpendicular to the faces of said clutch members whereby a relatively large proportion of the energy of said second clutch member is converted to torque for said first clutch member upon said impact engagement of said clutch members.

5. In a rotary impact tool, a cylindrical casing, a spindle journalled axially in one end of said casing, a clutch member journalled on said spindle and in the other end of said casing, a second clutch member slidably journalled on said spindle, said first and second clutch members having sector shaped teeth with square edges formed in predetermined spaced-apart relation on each of the mating faces of said clutch members, a bracket member secured axially on said spindle, and a plurality of elongated flat springs secured at opposite ends to said second clutch member and bracket member respectively, against axial movement with respect thereto for securing said second-named clutch member to said bracket member in spaced relationship and having the longitudinal axis thereof normally disposed in axial alignment with said spindle and the transverse axes thereof normally disposed in radial alignment with said spindle, said springs constituting the sole torque transmitting elements between said second clutch member and bracket member and being adapted to twist and shorten axially when torque is applied between said clutch members to lift the teeth of said second-named clutch member out of locking engagement with the teeth of said first-named clutch member upon application of a predetermined amount of torque between said clutch members, said springs being adapted to accumulate torque energy imparted thereto during engagement of said teeth and to drive said second-named clutch member along a helical path into impact engagement with said first-named clutch, said impacts being successive during application of said predetermined torque to impart successive torques to said first-named clutch substantially greater than the spindle.

torque imparted to said 2,049,273 Pott July 28, 1936 2,158,303 Pott May 16, 1939 2,196,589 Jimerson Apr. 9, 1940' 2,539,678 Thomas Jan. 30, 1951 FOREIGN PATENTS 592,916 Great Britain Oct. 2, 1947 1,091,048 France Oct. 27, 1954 

